EP0502098B1 - Variable area obstruction gas flow meter - Google Patents

Variable area obstruction gas flow meter Download PDF

Info

Publication number
EP0502098B1
EP0502098B1 EP91900481A EP91900481A EP0502098B1 EP 0502098 B1 EP0502098 B1 EP 0502098B1 EP 91900481 A EP91900481 A EP 91900481A EP 91900481 A EP91900481 A EP 91900481A EP 0502098 B1 EP0502098 B1 EP 0502098B1
Authority
EP
European Patent Office
Prior art keywords
conduit
leaves
leaf
obstruction
flow
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91900481A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0502098A4 (en
EP0502098A1 (en
Inventor
Josef Stupecky
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bicore Monitoring Systems
Original Assignee
Bicore Monitoring Systems
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bicore Monitoring Systems filed Critical Bicore Monitoring Systems
Publication of EP0502098A1 publication Critical patent/EP0502098A1/en
Publication of EP0502098A4 publication Critical patent/EP0502098A4/en
Application granted granted Critical
Publication of EP0502098B1 publication Critical patent/EP0502098B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
    • G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
    • G01F1/40—Details of construction of the flow constriction devices
    • G01F1/42—Orifices or nozzles
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Detecting, measuring or recording devices for evaluating the respiratory organs
    • A61B5/087—Measuring breath flow
    • A61B5/0876—Measuring breath flow using means deflected by the fluid stream, e.g. flaps
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
    • G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
    • G01F1/40—Details of construction of the flow constriction devices

Definitions

  • the present invention relates to flow meters, and in particular to a variable area obstruction in a conduit for use with a pressure transducer, particularly in medical applications, for measuring bi-directional flow rate of fluids such as respiratory gas in the conduit.
  • a flow meter is typically installed in a breathing conduit in close proximity to a patient.
  • the flow meter is exposed to a flow of warm air at body temperature that is 100% saturated with water vapor and contains airborne droplets of water, saliva or mucus. These airborne droplets can collect in the flow meter and adversely affect its operation.
  • water vapor normally condenses on inner surfaces of conduits installed in breathing circuits. The water droplets formed by this condensation glide along the inner walls of the conduit, and frequently collect in, and impede operation of, the flow meter.
  • the flow meter response When used in applications where a wide range of breathing flow rates are to be measured, it is very desireable that the flow meter response, as reflected in its output signal, be substantially linear, so that the sensitivity of the meter and accuracy of its readings is the same at low fluid flow rates as at high fluid flow rates.
  • the flow meter response when very low flow rates are being measured, then it is often desireable to produce a flow meter response which changes substantially in response to small changes in the flow rate, thereby enabling more accurate monitoring of the measured flows.
  • sterility requirements in critical care applications, such as operating room require that the flow meter be disposable. This dictates a very low production cost, while still necessitating a high sensitivity and accuracy for each individual flow meter.
  • this device cannot be used for the long term monitoring of respiratory air flow, since moisture or mucus collecting on the bundle of small diameter tubes produces a significant, adverse effect on the output signal of the device. Also, because of the linear response produced throughout the entire range of measurement, this device is not suited for application where a non-linear response is desireable at low flow rates, with a linear response produced at higher flow rates.
  • Fleisch pneumotachograph Another problem associated with the Fleisch pneumotachograph is its mechanical complexity, which in turn requires a high production cost. The high production cost makes the unit essentially non-disposable. Because it is not disposable, the requirement that the device be cleaned and sterilized after each patient use adds additional cost to the use of this device. The problems encountered in use of the Fleisch pneumotachograph are also experienced in the use of other popular flow meters, such as the ultrasonic, hot wire and turbine pneumotachographs.
  • flow meters may be of simple design, but are either too bulky for use in critical care applications, or they produce a non-linear output signal in a flow range where a linear signal is desired, or they have a limited measuring range.
  • These types of flow meters include the fixed orifice, venturi tube and pitot tube meters. More specifically, the fixed orifice flow meter provides an output signal defining a curve which gets progressively steeper as the flow rate increases. This is true since the device operates under turbulent flow conditions, where the pressure differential is proportional to the square of flow rate. This characteristic is undesirable because of drastically reduced sensitivity at low flow rates. Thus, fixed orifice flow meters are generally used in applications having a limited range of flow rates which are likely to be encountered.
  • Variable obstruction flow meters have also been provided, which combine the simplicity and low cost of the fixed orifice flow meters with better low end sensitivity and linear characteristics that typically have been available only from pneumotachographs. Nevertheless, many existing variable area obstruction designs still suffer from certain drawbacks such as accumulation of moisture or liquids in areas immediately adjacent the variable obstruction. These flow meters have also been known to suffer from resonant vibration or flutter of the leaves which comprise the variable obstruction at low flow rates corresponding to resting breathing of the patient. Furthermore, reduced sensitivity is often experienced at low flow rates due to relatively large leakage area in the obstruction produced by the gaps between the flexible leaves which are apparent when the leaves are in their resting condition.
  • the large leakage area is usually a result of the type of material selected for use as the obstruction, and the manufacturing process selected for producing the obstruction.
  • the material utilized for the obstruction will also determine the obstructions predisposition to errors caused by unwanted deflection of the leaves due to gravitational or inertial forces.
  • US-A-3,989,037 discloses a flow measuring device wherein a flow pipe carries a membrane between flanges.
  • the membrane consists of a thin plastic foil which is divided into individual lengths by vertical cuts and a diagonal cut extending across the free pipe cross section.
  • US-A-4,083,245 discloses a gas flow measuring head consisting of a housing with a gas inlet and outlet lying in straight line. A diaphragm is placed across the housing in a space between the inlet and the outlet. The diaphragm is made of an elastic material and has a hole produced by a partly cut-out section which forms a flap connected to the diaphragm and fitting the hole in size and shape.
  • US-A-4,006,634 discloses a flow meter with a variable area obstruction mounted in a conduit and a differential pressure transducer having its two ports mounted on opposite sides of the obstruction in fluid communication with the conduit.
  • the variable area obstruction is formed of one or more flexible leaves which extend into the flow stream and are deflectable under the influence fluid pressure, such that an increased flow rate increases the deflection of the leaves and decreases the area of the obstruction.
  • the invention relates in one aspect to a flow meter as claimed in claim 1.
  • the invention relates to a variable area diaphragm as claimed in claim 8.
  • variable area obstruction includes three elastic flexible leaves.
  • a primary leaf is formed with its fixed end or base being substantially centered about a center line running from the center of its free end to the base.
  • the base is secured adjacent the inner surface of the sleeve along a portion of the inner surface which is opposite to the sensing ports.
  • This primary leaf defines a portion of a substantially circular configuration, wherein the diameter of the circular portion of this leaf is smaller than the inner diameter of the sleeve.
  • the circular portion of the primary leaf is offset with respect to the center of the conduit, so that the free end of the primary leaf is substantially adjacent to a portion of the inner surface of the sleeve in a location which is substantially opposite to the center of the fixed end of the primary leaf.
  • the free end of the center leaf is positioned adjacent to the inner surface of a portion of the sleeve which is near the sensing ports.
  • a pair of secondary leaves of asymmetrical shape are defined on the primary leaf by a pair of cut lines extending from each side of the base of the primary leaf to termination points on the distal portion of the primary leaf and in a direction angled inward toward the center of the free end of that leaf.
  • the primary leaf in response to fluid flowing through the sleeve within the conduit, the primary leaf initially flexes about its base, and then the secondary leaves begin to flex about locations on the primary leaf between the termination of the cut lines and the free end of the primary leaf.
  • the primary leaf is the first to respond to fluid flow, with the secondary leaves subsequently beginning to flex. Accordingly, at low flow rates the pressure differential across the obstruction changes in a nonlinear fashion with respect to any change in the rate of any fluid flow through the conduit. However, as fluid flow rate increases to the point that the secondary leaves begin to flex, such flexing causes further changes in the pressure differential across the obstruction to be substantially linear with respect to any further change in rate of fluid flow through the conduit.
  • the leaves are formed by etching a very narrow continuous gap through the thickness of the diaphragm, creating a gap between the leaf edges and adjacent structures which is very small, in order to minimize leakage of the fluid through the obstruction. Due to this minimal leakage path through the obstruction, sensitivity and accuracy at very low flow rates are drastically improved. The upper range linearity is also improved since the active flexing area of the obstruction is, in the preferred embodiment, approximately 94% of the total conduit area. Therefore, since the leaves are configured in such a manner that they, while deflected, leave a substantially unobstructed passage along the fluid conduit wall, choking of the fluid flow happens at much higher flow rates than occurs in flow meters of other designs.
  • variable area obstruction in manufacturing the variable area obstruction from a single piece of thin material such as stainless steel allows the gaps between leaves to be formed with very high accuracies, and at very low costs.
  • the flow meter described herein is of a type which has a light, simple and very inexpensive structure, which is substantially unaffected by the water vapor and liquid present in respiratory air flow, and which can be mass produced while maintaining high accuracy and reliability in reproduction of each unit.
  • Figure 1 is a longitudinal sectional view of a variable area obstruction flow meter.
  • Figure 2 is a transverse sectional view taken along lines 2-2 of the flow meter of Figure 1, illustrating the configuration of the leaves in the obstruction diaphragm when the leaves are not deflected.
  • Figure 3 is a side sectional view of the obstruction diaphragm, taken along lines 3-3 of Figure 2, but with the leaves in partially deflected configuration as illustrated in Figure 1.
  • Figure 4 is a transverse sectional view taken along lines 2-2 of the flow meter of Figure 1, illustrating the configuration of the leaves in the obstruction diaphragm with the leaves in partially deflected configuration, as in Figure 3.
  • Figure 5 is a graphical illustration of flow rate versus pressure differential as measured by a flow meter of the type illustrated in Figures 1-4.
  • Figure 6 is a graphical illustration of flow rate versus pressure differential, showing predicted results based upon theoretical characteristics as defined by mathematical formulas representing the flow meter, and also showing actual test results produced by a prototype of the flow meter illustrated in Figures 1-4.
  • Figure 7 is a front elevational view of one preferred embodiment of an obstruction diaphragm for use in the variable area obstruction flow meter of the present invention, illustrating the obstruction diaphragm when the leaves are not deflected.
  • Figure 8 is 2 side sectional view of the obstruction diaphragm, taken along lines 8-8 of Figure 7, but with the leaves in a partially deflected configuration.
  • Figure 9 is a front elevational view of the obstruction diaphragm of Figure 6, illustrating the configuration of the leaves in the obstruction diaphragm
  • Figures 1-6 do not relate to the invention, but are present merely to aid comprehension. with the leaves in partially deflecter configuration, as in Figure 8.
  • Figure 10 is a graphical illustration of flow rate versus pressure differential, showing test results produced by the variable area obstruction flow meter of the present invention, using the obstruction diaphragm of Figures 7-9.
  • a flow meter generally indicated at 10 is interposed in a conduit 12 so as to permit the through flow of fluid through the conduit 12 and the flow meter 10 in the direction of arrows 14.
  • the flow meter 10 comprises a first section 16 which is substantially tubular in configuration, and which defines a first port 18 for communicating fluid between the bore of the first section 16 and the interior of conduit 12.
  • first pressure port 20 Extending through the body of the first section 16 is a first pressure port 20.
  • a first tube 22 is connected to the pressure port 20 so as to permit communication of fluid from the first section 16 through the first pressure port 20 and the tube 22 to a first sensor 24 of a differential pressure transducer 26.
  • the differential pressure transducer may comprise any of numerous such transducers which are well know and commercially available in the technology.
  • one preferred embodiment of a differential pressure transducer for use with the present invention comprises a Model NPH-8-015DH manufactured by Nova Sensors, Inc.
  • first flange or base 28 Extending inwardly from the first section 16 and, preferably, adjacent to the first pressure port 20, is a first flange or base 28 that supports an inner conduit wall 23 which defines a substantially concentric cylindrical sleeve configuration that extends parallel to the wall of section 16 between the first base and a free edge directed toward the first port 18.
  • the conduit wall 23, base 28 and parallel wall of section 16 form a dead end pocket 25 that extends adjacent to the first pressure port 20.
  • First base 28 is configured to be received, in mating relationship, with a second flange or base 30 extending inwardly from a second section 32.
  • the bases 28 and 30 are secured together along their adjacent surfaces by chemical or mechanical bonding or by other conventional fastening means.
  • second section 32 is configured as substantially a mirror image of the first section 16, and includes a second pressure port 36 which extends through the surface of the second section 32 so as to provide for communication of fluid from the second section 32, through the second pressure port 36 and through the bore of a second tube 38 connected to the second pressure port 36, to a second sensor 40 which is connected to the differential pressure transducer 26. Fluid is communicated between the interior of the second section 32 and the interior of conduit 12 via a second port 42.
  • the base 30 in the second section 32 supports an inner conduit wall 35 which defines a substantially concentric cylindrical sleeve configuration that extends parallel to the wall of section 32 between the second base 30 and a free edge directed toward the second port 42.
  • the conduit wall 35, base 30 and parallel wall of section 32 form a dead end pocket 37 that extends adjacent to the second pressure port 36.
  • variable area obstruction 44 comprises a membrane or diaphragm that preferably includes at least three flexible leaves, including a first outer leaf 46, a center leaf 48 and a second outer leaf 50.
  • the leaves 46, 48 and 50 are disposed so as to extend within the bore of sections 16 and 32, interior of the conduit walls 23 and 35 and, in the absence of fluid flow therethrough, to lie in a plane transverse to the direction of fluid flow therein.
  • the leaves 46, 48 and 50 deflect under the influence of moving fluid pressure in such a manner that an increased flow rate increases the deflection of the leaves 46, 48, and 50.
  • fluid flow through the flow meter 10 from port 42 to port 18 would cause a deflection of the leaves 46, 48 and 50 in the direction and manner illustrated in Figure 1.
  • the inner conduit walls 23 and 35 define a conduit bore which, because it is substantially separate from the walls of sections 16 and 32, is substantially free from condensation.
  • the configuration of the bases 28 and 30 and inner conduit walls 23 and 35 provide an inner conduit surface adjacent the leaves 46, 48 and 50 which is insulated from the ambient temperature communicated through the walls of sections 16 and 32.
  • the inner conduit walls 23 and 35 are enveloped by exhaled air, causing them and the leaves 46, 48 and 50 to assume the temperature of that exhaled air.
  • condensation does not occur on those surfaces and, therefore, condensed liquids are not transmitted from the walls 23 and 35 to the leaves 46, 48 and 50. Accordingly, interference in the leaf operation due to condensation is substantially avoided.
  • the inner conduit or sleeve formed by bases 28 and 30 and inner conduit walls 23 and 35 could also be formed by other structural configurations to produce an insulated inner conduit surface.
  • the bases 28 and 30 which, in the illustrated embodiment, extend about the central periphery of the sleeve, could be located in a different position.
  • other insulating material could be provided to support the sleeve, and could be located in at least a portion of the area between the walls of section 16 and 36 and the inner conduit walls 23 and 35.
  • the separation of the inner conduit walls 23 and 35 from the conduit walls of sections 16 and 32 prevent condensation from other portions of the flow meter 10 from influencing the operation of the leaves 46, 48 and 50.
  • liquid adhering to the inner walls of sections 16 and 32 and gliding along the conduit surfaces in other areas of the system will not reach the area occupied by leaves 46, 48 and 50, since this liquid will become trapped in one of the end pockets 25 or 37.
  • Those end pockets 25 and 37 also extend adjacent the pressure ports 20 and 36 so as to separate those pressure ports from direct communication with the through flowing fluid within the flow meter 10, and thus preventing turbulences localized around and downstream of the leaves 46, 48 and 50 from affecting the static pressure readings produced in the pressure transducer 26.
  • variable area obstruction 44 preferably comprises a diaphragm constructed of an elastic material such as very thin stainless steel shim. In one preferred embodiment, the obstruction 44 is approximately 0.001 inches in thickness.
  • the outer perimeter of the obstruction 44 is substantially circular, and includes at least one indexing cutout 52 for use in properly positioning the obstruction 44 between the sections 16 and 32. Corresponding indexing guides such as matched ridges and indentations or detents on adjacent surfaces of bases 28 and 30 can be provided to register the cutouts in proper positions.
  • a support border 53 is sandwiched between the mating surfaces of flanges 28 and 30 to structurally secure the obstruction 44 in position between sections 16 and 32. With the variable area obstruction 44 secured between sections 16 and 32, the approximate position of the interior surface of the inner conduit walls 23 and 35 with respect to the obstruction 44 is indicated by a dashed conduit bore surface line 54.
  • the first outer leaf 46, center leaf 48 and second outer leaf 50 are formed in the variable area obstruction 44 by etching a very narrow continuous gap 56 through the thickness of the variable area obstruction 44 along the path indicated in Figure 2.
  • the width of the gap 56 is exaggerated for clarity.
  • the gap is approximately 0,025 mm (0.001 inches) wide, resulting in a leakage area, when the leaves 46, 48 and 50 are in the unflexed state, of approximately 0,015 cm 2 (0.0023 square inch). This is at least a twenty fold improvement over the leakage area provided by other commercially available variable area flow meters.
  • the circular outside periphery of the obstruction 44, with indexing cutouts 52 is also formed during the etching operation.
  • the etching operation can comprise any of the well known chemical or electro-chemical etching techniques which are extremely accurate, and do not stretch or deform the material along the edges. Because of this etching technique, the variable area obstruction devices can be mass produced with substantially identical properties.
  • the leaves 46, 48 and 50 define a configuration which provides a substantially linear change in the pressure difference measured across the variable area obstruction 44 by the transducer 26, with respect to the change in flow rate through the bore of sections 16 and 32. To do this, the leaves 46, 48 and 50 provide a very small amount of leakage area in the absence of fluid flow, while defining a very limited obstruction to fluid flow at high flow rates. This response is achieved as a result of the leaf configuration illustrated in Figure 2.
  • the leaves 46, 48 and 50 are arranged so that they extend across the diameter of the conduit bore defined by the inner conduit walls 23 and 35 within sections 16 and 32 in an alternating, intertwining manner.
  • the obstruction 44 is secured between sections 16 and 32 so that the leaves 46, 48 and 50 lie within the conduit formed by inner conduit walls 23 and 35 in an orientation wherein the free end of leaf 48 extends toward pressure ports 20 and 22.
  • the width of the leaves at their free end is smaller than that at their fixed end.
  • the center leaf 48 is of trapezoidal configuration, with its fixed base defined by points 58 and 60, located adjacent the conduit bore surface line 54, with the base extending generally along line 54 between points 58 and 60.
  • the free end of leaf 48 defines an arch extending generally adjacent the conduit bore surface line 54 between points 62 and 64. In the illustrated embodiment, the distance between points 58 and 60 is twice the distance between points 62 and 64.
  • the first and second outer leaves, 46 and 50 are of asymmetrical shape with their free flexing ends terminating in a point at points 58 and 60, and curved along their outward edges to lie adjacent, near their points, to the conduit bore surface line 54.
  • the fixed ends of the first and second outer leaves, 46 and 50 are anchored along those portions of the conduit bore surface line 54 connecting points 62 and 66, and 64 and 68, respectively.
  • the bases of the outer leaves 46 and 50 are angularly oriented with respect to a center line extending longitudinally along the center of leaf 48.
  • the outer leaves 46 and 50 respond to fluid flow through the obstruction 44 by both bending and twisting about their fixed ends, so that as fluid flow increases, the curved outer portions of leaves 46 and 50 tend to remain adjacent to the inner surface of sections 16 and 32.
  • This characteristic of the leaves can be more fully appreciated by reference to Figure 3.
  • the center leaf 48 responds to such fluid flow by bending in a symmetrical manner about its fixed end, with substantially no longitudinal twisting of that center leaf.
  • center leaf 48 With the center leaf 48 extending upwardly within the flow meter 10, as illustrated, airborne droplets of water, saliva and mucus will sink downward to the base of the center leaf 48 and will, therefore, not impede the free movement of the free end of that center leaf 48. This permits the use of the flow meter in a breathing circuit which can be very close to the patient, while minimizing adverse effects of airborne liquids on device operation.
  • the center leaf 48 occupies approximately 44% of the area of the obstruction 44 located within the circular area defined by the conduit bore surface line 54.
  • the outer leaves 46 and 50 each represent approximately 25% of that total area.
  • the active, or flexible portion of the variable area obstruction 44 which includes the leaves 46, 48 and 50, comprises approximately 94% of the area defined within the conduit bore surface line 54. Accordingly, as the rate of fluid flow increases, the variable area obstruction 44 is able to respond by providing a very limited obstruction to the through passage of fluid, while providing a very minimal fluid leakage path during periods of low fluid flow rate.
  • Figure 3 illustrates a sectional view of the variable area obstruction 44, with the leaves 46 and 48 partially deflected. From this view, it can be more fully appreciated that deflection of the center leaf 48 produces substantially no twisting, but bending occurs about the fixed end portion of that leaf. In contrast, it is noted that the first outer leaf 46 experiences both bending and twisting about its fixed end, between points 64 and 68. Since the second leaf 50 (not shown) is asymmetrical with respect to leaf 46, it will bend and twist about its fixed end in a different direction. Accordingly, the leaves 46, 48 and 50 lie in different planes, with respect to each other, when they are deflected. This condition results in progressively faster increases in the flow area provided by the variable area obstruction 44 at higher flow rates. This provides for the substantially linear relationship between the change in differential pressure measured by transducer 26 with respect to the change in fluid flow rate through the variable area obstruction 44.
  • trace 70 represents the ideal characteristic of a flow meter producing a substantially linear relationship between the change in pressure measured through the meter and the change in flow rate.
  • the actual characteristic trace 72 relating to the flow meter 10, is very close to the ideal characteristic trace 70.
  • the trace lines illustrated in Figure 5 cover a range of flow rates extending from .016 liters per second to 2.6 liters per second.
  • the linearity of the trace line 72 at lower flow rates is a result of the minimal leakage path through the obstruction 44 which is present at those low flow rates.
  • Linearity at the upper end of the flow rates is also improved over other devices, because the active flexing area of the obstruction 44 in the flow meter 10 comprises approximately 94% of the total area within the conduit bore surface line 54. Accordingly, choking of the flow occurs at much higher levels of flow than in devices which do not provide such a large active flexing area of the obstruction.
  • Figure 6 illustrates a comparison of the theoretical results represented by theoretical characteristic trace 74 as compared with the actual results determined in testing of a prototype, represented by the actual characteristic trace 76.
  • the prototype flow meter that produced the actual characteristic trace 76 was constructed pursuant to criteria and design parameters listed below:
  • variable area obstruction 44 The sizing of the variable area obstruction 44 is a complex task. There are many factors which influence the flow versus pressure drop relationship. Secondary turbulences, caused by deflection of the air stream by the flexing leaves and interference of individual streams of air as they merge after passing though the variable area obstruction, create an additional pressure drop which is not accounted for by formulas.
  • K The numerical value of K for the prototype incorporating the variable area obstruction 44 of Figures 2-4 is determined by substituting the test data for that prototype into Equation 11.
  • Q 3.738 x 10 -9 x l 5 t 3 x p
  • FIG. 7-9 Another preferred embodiment of the invention provides for a substantially linear relationship between the change in pressure differential and change in flow rate at higher flow rates, while having increased sensitivity of the pressure differential with respect to changes in flow rates at low flow rates. This embodiment of the invention is illustrated in Figures 7-9.
  • Figure 7 illustrates another preferred embodiment of a variable area obstruction generally indicated at 80, for use in the flow meter of Figure 1.
  • the variable area obstruction 80 is constructed in a manner substantially the same as that of the variable area obstruction 44, illustrated in Figures 2-4, with the exception of the configuration of the leaves in the active flexing area bounded by the conduit bore surface line 54.
  • variable area obstruction 80 comprises a primary leaf 82, with its fixed base extending generally along line 54 between points 84 and 86. From points 84 and 86, the parameter of the primary leaf 82 is defined by the very narrow, continuous gap 56 which is etched in the obstruction 80. In particular, from points 84 and 86, the gap 56 travels along a substantially straight, inwardly directed line to points 88, and 90, respectively, defining a short neck between the base and points 88 and 90. Points 88 and 90 are connected to each other by the gap 56 in a manner which forms a substantially circular configuration, within the diameter of the conduit bore surface line 54.
  • the circular portion of the primary leaf 82 is offset with respect to the center of the area within the conduit bore surface line 54, so that the free end 92 of the primary leaf is substantially adjacent to a portion of the conduit bore surface line 54 at a location which is substantially opposite to the center of the fixed end of the primary leaf 82.
  • a pair of secondary leaves 94 and 96 of asymmetrical shape are defined on the primary leaf 82 by extensions of the gap line 56.
  • secondary leaf 94 is defined by a portion of the primary leaf 82 which extends outwardly from the center of the primary leaf 82, and lies on the opposite side of a substantially straight extension of the gap 56 running from point 88 to a termination point 98 on the distal portion on the primary leaf 82.
  • secondary leaf 96 is defined by that portion of the primary leaf 82 extending outward from the center of the primary leaf, and lying on the other side of a substantially straight portion of the gap 56 extending from the point 90 to a termination point 100 on the distal portion of the primary leaf 82.
  • the substantially straight gap segments between points 88 and 98 and points 90 and 100, respectively, are directed generally inwardly from the points 88 and 90 to the points 98 and 100, respectively, toward the center of the free end of the primary leaf 82.
  • the free flexing ends of secondary leaves 94 and 96 terminate at points 88 and 90, respectively.
  • the secondary leaves 94 and 96 comprise a base which is generally defined by the region of the primary leaf 82 which extends generally downwardly and outwardly from the points 98 and 100, respectively, to the gap 56.
  • the secondary leaves 94 and 96 are arranged so that their fee flexing ends extend in a direction opposite to that of the primary leaf 82, with the base portion of the primary leaf 82 interposed between the free ends of the secondary leaves 94 and 96 so that the leaves are arranged with their free ends oriented in alternately opposing directions.
  • the primary leaf 82 responds to fluid flow through the obstruction 80 by bending about its fixed end in the region defining a neck, between points 84 and 88, and 86 and 90, respectively.
  • the primary leaf 82 does not experience substantial twisting.
  • the secondary leaves 94 and 96 respond to fluid flow through the obstruction 80 by both bending and twisting about their fixed ends, so that as fluid flow increases, and as the primary leaf 82 bends about its fixed end, the secondary leaves 94 and 96 bend and twist about their fixed ends so their free ends are deflected in a generally inwardly direction, such that the curved outer portions of the secondary leaves 94 and 96 tend to remain adjacent to the inner surface of sections 16 and 32.
  • the initial response to fluid flowing through the conduit at lower flow rates is that the primary leaf 82 initially flexes about its fixed end. No substantial independent flexing is exhibited by the secondary leaves 94 and 96 at the low flow rates.
  • the flow rates creating this response vary depending on the size of conduit and other variables as was discussed in connection with the embodiment of Figures 2-4. However, for example purposes, low flow rates through a conduit of about 1,52 cm (0.60 inch) diameter would be in the range of 0 to 0.5 liters per second.
  • the secondary leaves 94 and 96 begin to flex about their fixed locations on the primary leaf. Accordingly, at low flow rates, the pressure differential across the obstruction changes at a rate which is greater than the change in the rate of fluid flow, thus creating a non-linear response at low flow rates. However, as flow rates through the obstruction 80 increase to the point that the secondary leaves 94 and 96 begin to flex, that additional flexing increases the rate at which an opening is created through the obstruction 80, so that the further changes in the pressure differential across the obstruction 80 are substantially linear with respect to further changes in the rate of fluid flow through that obstruction 80.
  • the primary leaf 82 and the secondary leaves 94 and 96 can respond to increased fluid flow by providing a very limited obstruction to the through passage of fluid, while still providing a very minimal fluid leakage path during periods of low fluid flow rate.
  • the active, or flexible portion of the variable area obstruction 80, including leaves 82, 94 and 96 comprises approximately 94% of the area defined within the conduit bore surface line 54.
  • the response of the primary and secondary leaves with respect to fluid flow can be more fully appreciated.
  • the leaves 82, 94 and 96 lie substantially parallel in plane 101, which is substantially transverse to the direction of fluid flow indicated at 83.
  • the leaf position at low fluid flow rates is generally illustrated at 102, by phantom lines.
  • the primary leaf 82 is bending, without substantial twisting, about the neck region defined at the fixed end of the primary leaf 82, but no substantial bending or flexing of the secondary leaves 94 and 96 is experienced.
  • the leave position at higher rates of fluid flow through the obstruction 80 is illustrated generally at 104.
  • the primary leaf 82 is more fully flexed in a bending configuration about the neck adjacent its fixed end.
  • the secondary leaves 94 and 96 also both bend and twist about their fixed ends, in the region, respectively, between point 98 and the adjacent gap 56, and point 100 and the adjacent gap 56.
  • the leaves 82, 94 and 96 each lie in different plains with respect to one another, when flexed in response to higher fluid flow rates as illustrated in Figure 8. This condition results in progressively faster increases in the through flow area provided by the variable area diaphragm obstruction 80 at higher flow rates.
  • the embodiment of Figures 7 and 8 provides for a non-linear relationship between the parameters, wherein the change in pressure differential across the obstruction 80 is greater than the change in rate of fluid flow through the variable area obstruction 80.
  • Figure 10 provides a graphical illustration of the reverse parabolic configuration which characterizes a plot of flow with respect to pressure differential through the variable area obstruction 80 at flow rates at or less than about one-half liter per second. It is noted that the pressure differential ⁇ p0 to ⁇ p1 experienced in the low flow rate region defined between Q0 and Q1 is in the range of about two times as sensitive as the pressure differential ⁇ p2 to ⁇ p3 measured in response to the same flow rate changes in the higher flow regions between Q2 and Q3 in the graph of Figure 10.
  • the invention described herein comprises a significant improvement over the prior art by providing a flow meter having a configuration which, in one preferred embodiment, provides a substantially linear relationship between the change in pressure differential across the obstruction and changes in fluid flow rate across that obstruction.
  • a substantially non-linear relationship exists between change in pressure differential and change in fluid flow through the obstruction at lower flow rates, with a substantially linear relationship existing between these elements at higher flow rates.
  • the invention also overcomes other long existent problems in the industry by (1) providing a flow meter having a wide measuring range and accuracy, which is substantially not affected by the presence of moisture or mucus produced by a patient; (2) providing such a flow meter wherein the size of the flow passage in the variable area obstruction is minimized at zero flow condition; (3) providing such a flow meter that has a light, simple and inexpensive structure which permits it to be disposable while being manufactured in a manner that allows mass production while maintaining the high level of sensitivity and accuracy in each unit; and (4) providing such a flow meter where the active area of the variable obstruction is substantially the same as the full cross sectional area of the fluid conduit, and wherein the elements of the variable area obstruction are shaped in such a manner that they, at maximum deflection, leave a substantially unobstructed passage along the fluid conduit wall.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Biomedical Technology (AREA)
  • Surgery (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Physiology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Pulmonology (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Measuring Volume Flow (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
EP91900481A 1989-11-06 1990-11-05 Variable area obstruction gas flow meter Expired - Lifetime EP0502098B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US07/432,041 US4989456A (en) 1989-11-06 1989-11-06 Variable area obstruction gas flow meter
PCT/US1990/006411 WO1991006830A1 (en) 1989-11-06 1990-11-05 Variable area obstruction gas flow meter
US432041 1999-11-01

Publications (3)

Publication Number Publication Date
EP0502098A1 EP0502098A1 (en) 1992-09-09
EP0502098A4 EP0502098A4 (en) 1993-07-21
EP0502098B1 true EP0502098B1 (en) 1997-01-22

Family

ID=23714505

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91900481A Expired - Lifetime EP0502098B1 (en) 1989-11-06 1990-11-05 Variable area obstruction gas flow meter

Country Status (8)

Country Link
US (1) US4989456A (xx)
EP (1) EP0502098B1 (xx)
JP (1) JP2980979B2 (xx)
AT (1) ATE148223T1 (xx)
CA (1) CA2073006C (xx)
DE (1) DE69029810T2 (xx)
HK (1) HK1007795A1 (xx)
WO (1) WO1991006830A1 (xx)

Families Citing this family (76)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5141029A (en) * 1990-12-19 1992-08-25 Eastman Kodak Company Variable orifice device
US5454375A (en) * 1993-10-21 1995-10-03 Glottal Enterprises Pneumotachograph mask or mouthpiece coupling element for airflow measurement during speech or singing
US5564432A (en) 1994-07-13 1996-10-15 Thomson; Ronald A. Biodegradable air tube and spirometer employing same
US5816246A (en) * 1994-09-15 1998-10-06 Mirza; M. Zubair Electronic pocket spirometer
US5583301A (en) * 1994-11-09 1996-12-10 National Environmental Products Ltd., Inc. Ultrasound air velocity detector for HVAC ducts and method therefor
US5901751A (en) * 1996-03-08 1999-05-11 Applied Materials, Inc. Restrictor shield having a variable effective throughout area
US5743270A (en) * 1996-06-21 1998-04-28 Desert Moon Development Limited Partnership Resistive element for spirometer
US5715831A (en) * 1996-06-21 1998-02-10 Desert Moon Development Limited Partnership Calibrated air tube for spirometer
US5997483A (en) * 1996-06-21 1999-12-07 Desert Moon Development Limited Partnership Individualized and calibrated air tube for spirometer
US5789660A (en) 1996-07-15 1998-08-04 Novametrix Medical Systems, Inc. Multiple function airway adapter
US7335164B2 (en) 1996-07-15 2008-02-26 Ntc Technology, Inc. Multiple function airway adapter
US20070225612A1 (en) * 1996-07-15 2007-09-27 Mace Leslie E Metabolic measurements system including a multiple function airway adapter
US5693079A (en) * 1996-08-19 1997-12-02 Augustine Medical, Inc. Apparatus and method for simulating an inflatable thermal blanket to test an air source
US5988876A (en) * 1997-07-15 1999-11-23 Augustine Medical, Inc. Method for measuring temperature of an airflow for an inflatable thermal device
US5925831A (en) * 1997-10-18 1999-07-20 Cardiopulmonary Technologies, Inc. Respiratory air flow sensor
US6126610A (en) * 1997-11-03 2000-10-03 Novametrix Medical Systems, Inc. Pneumatic connector with encoding
US6099481A (en) 1997-11-03 2000-08-08 Ntc Technology, Inc. Respiratory profile parameter determination method and apparatus
US5970801A (en) 1997-12-30 1999-10-26 Bear Medical Systems, Inc. Variable orifice flow sensor
US6358058B1 (en) 1998-01-30 2002-03-19 1263152 Ontario Inc. Aerosol dispensing inhaler training device
US20050121033A1 (en) * 1998-02-25 2005-06-09 Ric Investments, Llc. Respiratory monitoring during gas delivery
US6544192B2 (en) * 1998-02-25 2003-04-08 Respironics, Inc. Patient monitor and method of using same
US6017315A (en) 1998-02-25 2000-01-25 Respironics, Inc. Patient monitor and method of using same
KR19980025075U (ko) * 1998-04-27 1998-07-25 이경용 1회용의 의료용 내시경 감염방지기구
USD413825S (en) * 1998-09-14 1999-09-14 Cardiopulmonary Technologies, Inc. Respiratory air flow measuring device
DE19923077A1 (de) * 1999-05-20 2000-11-23 Leybold Systems Gmbh Beschichtungsanlage
FR2816820B1 (fr) * 2000-11-17 2003-10-17 Chanoine Philippe Le Appareil de mesure de debits respiratoires
US20030097880A1 (en) 2001-11-29 2003-05-29 Ciobanu Calin I. Multi-stage variable orifice flow obstruction sensor
US7387123B2 (en) * 2001-11-30 2008-06-17 Viasys Manufacturing, Inc. Gas identification system and volumetrically correct gas delivery system
US7878980B2 (en) 2003-06-13 2011-02-01 Treymed, Inc. Gas flow diverter for respiratory monitoring device
US7028560B2 (en) * 2003-06-24 2006-04-18 Pontificia Universidad Católica del Peru Method to linearly measure gas volume flow in ducts and flow sensor
US7270143B2 (en) * 2005-03-16 2007-09-18 The General Electric Company Offset variable-orifice flow sensor
US7337678B2 (en) * 2005-12-09 2008-03-04 General Electric Company MEMS flow sensor
US8474455B2 (en) * 2006-01-10 2013-07-02 Carefusion 207, Inc. System and method for circuit compliance compensated volume assured pressure control in a patient respiratory ventilator
US20080029173A1 (en) * 2006-08-07 2008-02-07 Diperna Paul Mario Variable flow reshapable flow restrictor apparatus and related methods
DE102006037537B4 (de) * 2006-08-10 2008-05-08 Airbus Deutschland Gmbh Blende sowie deren Verwendung zum Drosseln eines Volumenstroms in einem Luftverteilungsrohrsystem einer Klimaanlage eines Verkehrsflugzeuges
WO2008037594A1 (de) * 2006-09-28 2008-04-03 Continental Automotive Gmbh Vorrichtung zur regelung, eines vom volumenstrom bestimmten druckverlaufs, innerhalb eines vorgegebenen grenzbereichs
BRPI0703836B8 (pt) * 2007-09-06 2018-09-18 Intermed Equipamento Medico Hospitalar Ltda sensor de fluxo de dupla obstrução
US20100145635A1 (en) * 2007-12-03 2010-06-10 Aqua Digital Ltd. Vane type flow meter with two or more measuring ranges
US8986253B2 (en) 2008-01-25 2015-03-24 Tandem Diabetes Care, Inc. Two chamber pumps and related methods
US8215340B2 (en) * 2008-02-19 2012-07-10 Daniel Measurement And Control, Inc. Orifice plate carrier
US20100036327A1 (en) * 2008-08-08 2010-02-11 Tandem Diabetes Care, Inc. Flow prevention, regulation, and safety devices and related methods
US8408421B2 (en) * 2008-09-16 2013-04-02 Tandem Diabetes Care, Inc. Flow regulating stopcocks and related methods
WO2010033878A2 (en) 2008-09-19 2010-03-25 David Brown Solute concentration measurement device and related methods
AU2010217760B2 (en) 2009-02-27 2015-04-09 Tandem Diabetes Care, Inc. Methods and devices for determination of flow reservoir volume
US9250106B2 (en) 2009-02-27 2016-02-02 Tandem Diabetes Care, Inc. Methods and devices for determination of flow reservoir volume
CA2756710C (en) * 2009-04-27 2013-06-04 Rostrum Medical Innovations Inc. Apparatus and method for monitoring the degree of integration between the functions of the heart and the lungs, and the therapeutic success of resuscitative interventions
EP3284494A1 (en) 2009-07-30 2018-02-21 Tandem Diabetes Care, Inc. Portable infusion pump system
US8276618B2 (en) * 2010-05-18 2012-10-02 Mindray Medical Sweden Ab Flow restrictor and method for reducing resistance of a flow
GB2499995B (en) * 2012-03-05 2018-01-31 Spirax-Sarco Ltd Flow meter
US9180242B2 (en) 2012-05-17 2015-11-10 Tandem Diabetes Care, Inc. Methods and devices for multiple fluid transfer
US9046394B2 (en) * 2013-01-07 2015-06-02 Sensus Spectrum Llc Water meter including variable orifice device
GB201300403D0 (en) 2013-01-10 2013-02-20 Smiths Medical Int Ltd Flow sensors and apparatus
US9173998B2 (en) 2013-03-14 2015-11-03 Tandem Diabetes Care, Inc. System and method for detecting occlusions in an infusion pump
US9046396B2 (en) 2013-03-15 2015-06-02 Dieterich Standard, Inc. Process variable measurement using universal flow technology connection platform
US9151648B2 (en) 2013-03-15 2015-10-06 Dieterich Standard, Inc. Process variable measurement using primary element connection platform
DE102013216127B4 (de) * 2013-08-14 2015-03-19 Eberspächer Climate Control Systems GmbH & Co. KG Strömungsverdämmungselement, insbesondere zur Luftströmungsverdämmung in einem Luftkanalsystem eines Fahrzeugs
US8939178B1 (en) * 2014-04-22 2015-01-27 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Variable-aperture reciprocating reed valve
US10059191B2 (en) 2014-07-01 2018-08-28 Denso International America, Inc. Low resistance flow regulator
US9329065B2 (en) * 2014-07-25 2016-05-03 General Electric Company Variable orifice flow sensor utilizing localized contact force
USD752463S1 (en) 2014-07-25 2016-03-29 General Electric Company Variable orifice flow sensor
US9823106B2 (en) 2014-07-25 2017-11-21 General Electric Company Flow sensor with heated air collar
US10005097B2 (en) 2014-11-05 2018-06-26 3M Innovative Properties Company Die for coating suspensions with flow obstruction device and method of use
AU2016270539B2 (en) * 2015-06-04 2020-10-22 Fluid Handling Llc Contoured insert for flow verification
US9597476B1 (en) * 2015-06-09 2017-03-21 Event Medical Ltd. Flow sensor and method
EP3112818B1 (de) * 2015-07-01 2020-02-26 imtmedical ag Atemstromsensor
US11890089B1 (en) * 2015-07-28 2024-02-06 Thorasys Thoracic Medical Systems Inc. Flowmeter for airway resistance measurements
US9909909B2 (en) * 2016-03-16 2018-03-06 Rosemount Inc. Flow measurement system for single-use containers
KR101898237B1 (ko) * 2016-12-21 2018-10-04 주식회사 포스코 유량 측정 장치 및 이를 포함하는 발전 설비
US10836990B2 (en) 2016-12-23 2020-11-17 Cyberoptics Corporation Sensor interface for single-use containers
US10584309B2 (en) 2017-02-06 2020-03-10 Rosemount Inc. Pressure transducer for single-use containers
DE102017206234A1 (de) * 2017-04-11 2018-10-11 Robert Bosch Gmbh Sensorelement zur Erfassung mindestens einer Eigenschaft eines fluiden Mediums
DE102018204800A1 (de) * 2018-03-28 2019-10-02 Hamilton Medical Ag Differenzdruck-Durchflusssensor für Beatmungsvorrichtungen mit verbesserter Entwässerung
DE102018204799A1 (de) 2018-03-28 2019-10-02 Hamilton Medical Ag Differenzdruck-Durchflusssensor für Beatmungsvorrichtungen mit verbessertem Strömungswiderstand mit mehrteiliger Klappe
JPWO2020208697A1 (xx) * 2019-04-09 2020-10-15
US11371902B2 (en) 2019-12-27 2022-06-28 Rosemount Inc. Process venting feature for use in sensor applications with a process fluid barrier
DE102021124785A1 (de) 2021-09-24 2023-03-30 Hamilton Medical Ag Durchflusssensor

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2941544A (en) * 1955-09-27 1960-06-21 Renault Fluid control devices and elastic pressure-responsive valves
US2989866A (en) * 1956-01-03 1961-06-27 Bendix Corp Cantilever beam flowmeter
US3232288A (en) * 1963-05-06 1966-02-01 Human Resources Foundation Respiratory analysis instrument
US3989037A (en) * 1970-06-23 1976-11-02 Siemens Aktiengesellschaft Flow measuring device
US4006634A (en) * 1975-09-17 1977-02-08 National Semiconductor Corporation Flow meter
US4083245A (en) * 1977-03-21 1978-04-11 Research Development Corporation Variable orifice gas flow sensing head
US4163390A (en) * 1977-04-14 1979-08-07 Rodder Jerome A Bipolar fluid measuring apparatus
JPS5791436A (en) * 1980-11-28 1982-06-07 Mitsubishi Electric Corp Detector for amount of suction air of internal combustion engine
US4599907A (en) * 1985-04-19 1986-07-15 Kraus Robert A Mass-flow sensing transducer
US4688433A (en) * 1985-07-15 1987-08-25 Pall Corporation Flow sensing device

Also Published As

Publication number Publication date
CA2073006C (en) 2001-03-20
DE69029810D1 (de) 1997-03-06
HK1007795A1 (en) 1999-04-23
JPH05506090A (ja) 1993-09-02
US4989456A (en) 1991-02-05
CA2073006A1 (en) 1991-05-07
EP0502098A4 (en) 1993-07-21
JP2980979B2 (ja) 1999-11-22
EP0502098A1 (en) 1992-09-09
ATE148223T1 (de) 1997-02-15
DE69029810T2 (de) 1997-08-21
WO1991006830A1 (en) 1991-05-16

Similar Documents

Publication Publication Date Title
EP0502098B1 (en) Variable area obstruction gas flow meter
US5038621A (en) Variable area obstruction gas flow meter
JP2968970B2 (ja) 流れ検知装置
US5535633A (en) Differential pressure sensor for respiratory monitoring
JP2778769B2 (ja) 気体の流れを絞り方向を制御する流量測定用の検出装置
JP4253125B2 (ja) 可変オリフィス流量センサ
US5379650A (en) Differential pressure sensor for respiratory monitoring
US5134890A (en) Fluid flow monitoring device
US5033312A (en) Gas flow meter housing
US7337678B2 (en) MEMS flow sensor
US4403514A (en) Pneumotachograph with pitot-like tubes
AU2008331575B2 (en) Airflow sensor with pitot tube for pressure drop reduction
US7270143B2 (en) Offset variable-orifice flow sensor
EP0988555B1 (en) Lift force fluid flow sensor for measuring fluid flow velocities
CA2086962A1 (en) Sidestream flow sensor for spirometry
EP0425120A2 (en) Averaging pitot probe
JPH0374570B2 (xx)
CA1146776A (en) Turbulence conveyor flow meter
CA1069342A (en) Variable orifice gas flow sensing head
GB2052074A (en) Pneumotachograph with Pitot- like Tubes
KR100682026B1 (ko) 소형 단방향 기류 계측용 호흡관
US20090204014A1 (en) Down-sized single directional respiratory air flow measuring tube
JPS6340967Y2 (xx)
JPH0115365Y2 (xx)
EP0192101A1 (en) A mass flow meter

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19920504

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE

RIN1 Information on inventor provided before grant (corrected)

Inventor name: STUPECKY, JOSEF

A4 Supplementary search report drawn up and despatched

Effective date: 19930528

AK Designated contracting states

Kind code of ref document: A4

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE

17Q First examination report despatched

Effective date: 19940930

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19970122

Ref country code: AT

Effective date: 19970122

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRE;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.SCRIBED TIME-LIMIT

Effective date: 19970122

Ref country code: CH

Effective date: 19970122

Ref country code: DK

Effective date: 19970122

Ref country code: ES

Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY

Effective date: 19970122

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19970122

Ref country code: BE

Effective date: 19970122

Ref country code: LI

Effective date: 19970122

REF Corresponds to:

Ref document number: 148223

Country of ref document: AT

Date of ref document: 19970215

Kind code of ref document: T

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REF Corresponds to:

Ref document number: 69029810

Country of ref document: DE

Date of ref document: 19970306

ET Fr: translation filed
NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19971105

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: FR

Ref legal event code: TP

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20051108

Year of fee payment: 16

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20061106

EUG Se: european patent has lapsed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20091029

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20091123

Year of fee payment: 20

Ref country code: GB

Payment date: 20091104

Year of fee payment: 20

REG Reference to a national code

Ref country code: GB

Ref legal event code: PE20

Expiry date: 20101104

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20101104

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20101105